Stats started showing strong performances towards the second half of 2014. He accumulated a very respectable 15-10 record in Proleague, including an outstanding 9-3 record against Zerg players. He also emerged victorious in the one ace match he played and won all 3 games he played during the playoffs, thus proving himself essential to KT's effort in winning the championship. He also made his first strong run in the GSL, where he finished top 8 with both of his losses coming at the hands of the eventual finalists. In October 2014, he won the World Esports Championship Games 2014: South Korea Qualifier. In November, he also managed to qualify for Hot6ix Cup in a strong qualifier run.

Stats's good form continued in 2015 with a semi-final finish in the 2015 StarCraft II StarLeague Season 1. In addition to that, Stats held a 14-3 record during 2015 Proleague Round 1 and 2, including an all-kill against SK Telecom T1 in the Round 2 playoffs, and a 100% win rate against Zerg. He continued to expand on this record and remained the top performer of his team until Zest overtook him with a perfect 7-0 run in the last round. Despite having a drop of form near the end of the season, Stats finished Proleague with a strong 22-12 record, including one ace match win for his team. He was also the final player sent out by KT to stop sOs from scoring a reverse all-kill in the Proleague playoffs. Unfortunately for Stats and his team, he was unable to do it and thus KT Rolster was the first team eliminated in the playoffs.

In the 2015 StarCraft II StarLeague Season 2, Stats was able to repeat his success by reaching the semi-finals again, but just like in Season 1, he lost 2-4, this time against the later champion Classic. In Season 3 of the tournament, he could not repeat his previous performances and was eliminated in a "group of death" in last place, losing to ByuL (the eventual runner-up) and Maru (who in turn was eliminated right afterwards by Zest).

Stats was one of only two players of KT Rolster who managed to qualify for both Code A and S2SL. He was then scheduled to face the up-and-coming Zerg player DeParture in Code A, and fellow Protoss player Hurricane in SSL.

The young MVP Zerg DeParture proved to be an obstacle Stats found himself unable to overcome in Code A. Though the series was tied at 1-1 after two games, DeParture ended up winning with a convincing 3-1 scoreline. For Stats, this marked his fourth consecutive failure to qualify for Code S.

However, while he continuously struggled with qualifying for Code S, Stats did find success in the SSL repeatedly. After his two top 4 finishes the previous year, Stats was looking to one-up his performance, as he had never reached the finals of a Premier individual competition in his eight-year long career. Six days after his loss to DeParture in Code A, Stats defeated Hurricane to advance another round in the winner bracket of the SSL. There, he would face another Protoss player, Patience. Stats prevailed, winning 3-1 and reaching the semifinals of the winner bracket. There, his opponent Dark shut him down completely, taking a convincing 3-0 victory with aggressive play.

And so, Stats's battle through the loser bracket begun. First, he had to face the resurgent ByuN, the last Terran left in SSL. In an action packed and close series that featured Carriers, Stats managed to barely edge out a 3-2 victory. With this win, Stats had reached the top 4 of the tournament and thus repeated his performance of 2015's first season of SSL. Now, he would be forced to face Patience in a rematch. The Protoss player, then on team Dead Pixels, was on a strong run through the loser bracket himself, scoring consecutive wins over soO, Classic, and RagnaroK, the latter of which had reached the semifinals of the winner bracket with wins against INnoVation and ByuN. Despite this, the series was completely one-sided. Stats showed superiority to Patience in all aspects of the game and won 4-0.

Stats was now a single match away from reaching the Grand Finals of SSL, one step closer to becoming a champion. However, in his was one more giant obstacle: Solar. Solar had been the most successful Zerg player since the release of Legacy of the Void, and he had won 41 consecutive matches in ZvP.[1] Stats's PvZ had not looked powerful up to this point. However, Stats took a rather quick 2-0 lead with solid macro play. Then Solar, with a 2-base all-in and the clever usage of banelings, won three maps in a row. But this time, unlike the two previous times Stats had reached the top 4 in SSL, he recovered from the 2-3 deficit. First, he won another solid macro game on Lerilak Crest to bring the series to the deciding game on Ulrena. There, Solar intended to utilize the map's architecture in his favor, opting for a Speedling/Queen all-in via the shortest ground path. However, Stats had fully walled of his natural base, and with good usage of all of his units and continuous reinforcing of the wall, he left Solar with no choice but to tap out.

His opponent in the Grand Finals was once again Dark, who had defeated Stats in their first meeting of the year. Dark was highly favored in the eyes of fans in Korea,[2] as well as experts,[3][4] for this rematch. Stats was caught off guard by Dark's playstyle, as the Zerg's ling/bane composition, as well as his heavy drop play, and brood lord transitions in the late game, as this sort of play was extremely uncommon at the time. Stats quickly found himself down in their match, however, he fought back and slowly began to adapt to his opponent's new style. In spite of this, Dark eventually closed out the series with a 4-2 score.

His second-place finish rewarded him with an opportunity to play in the first ever WCS Korea Cross Finals. In this competition, the two finalists of the SSL and the two finalists of the GSL would face off for over $25,000 of prize money in total, as well as 1,000 crucial WCS points. The first part of the Cross Finals was an Archon Mode match with Team SSL (Dark and Stats) taking on Team GSL (Stats's teammates Zest and TY). Both teams opted to play Protoss for nearly every map, with a single TvZ mixed in. Team GSL won the match with a 3-1 score. Following that, Stats would have to take on Zest, the recent GSL Champion and by consensus best player in the world at the time.[5]

Stats emerged victorious, showing his prowess in the PvP match-up, and taking Zest down 3-1. On the other half of the bracket, Dark defeated TY 3-2 in a very close series, meaning the two SSL finalists would meet for a rematch. This time, Stats kept the upper hand. A few minor hiccups cost him the game on Dusk Towers, but Stats was in complete control of the series overall, eventually winning with another 3-1 score. Aside from more than $17,000 of prize money and the 1,000 WCS points that brought him one step closer to reaching the Global Playoffs, this marked Stats's first big win in an individual tournament.

A day later, Stats played in the finals of the first Kung Fu Cup of 2016. He had dominated the tournament up to that point, losing only two maps, one against Solar and one against TY. His opponent in the finals was TY again, coming in off the back of a strong run through the loser bracket. The series was an intense back and forth, but Stats prevailed, securing the 4-3 win on the final map.

Aside from his success in individual leagues, Stats has remained a core contributor for his team KT in Proleague. In the regular season of round 1, he scored 4 wins and conceded only 2 losses, making him one of the top 10 players for that round. In the playoffs, he earned himself 4 additional wins, taking out aLive, Curious, Bomber and sOs, whilst losing to KeeN and Maru. In the playoffs for round 2, he once again all-killed SK Telecom T1.

Once known as "Chintoss" for his distinctive chin. Korean fans called him "Wallytoss" for the same reason as it was widely claimed that he resembled Wally from "Where's Wally?". After corrective surgery, it is no longer as distinctive, however, the nicknames remained.

In the Korean community, Stats is known for losing many probes to Spider/Widow Mines, which started with his match against Leta in Brood War (GIF / video highlight). The clip turned into a meme in Korea, complete with caster reactions, terrible Dragoon AI and Stats' devastated headshake. His name has become synonymous with Widow Mine explosions - the term "머-엽" ("Stats'd") is widely used to refer to Widow Mine connections (and more generally, explosions) that wipe out a large number of units at once.